1. Field of the Invention
This invention relates to a method for determining a temperature by means of a radiation thermometer with multiple infrared sensor elements, and to a thermometer of this type.
2. Description of the Related Art
The art knows of radiation thermometers having just a single infrared sensor element disposed at a predetermined distance from the end of an optical waveguide. In consequence, radiation can impinge on the sensor element only from a predetermined, distance-dependent solid angle range. Thus, for instance, the probe head of an infrared thermometer designed to take a patient's temperature in the ear is dimensioned such that the sensor element exhibits a field of view only of the approximate size of the tympanic membrane. However, the field of view of the sensor element usually covers parts of both the tympanic membrane and the ear canal exhibiting differing temperatures. Generally, therefore, not the tympanic temperature is taken, which is considered as being representative of the true body core temperature, but rather an intermediate value that lies between the tympanic and the ear canal temperature. Hence the accuracy of a temperature reading depends on the placement of the probe head in the ear canal, that is, on its distance to the tympanic membrane and on the angle it forms with the ear canal.
From WO 95/14913 an ear thermometer is known in which multiple sensor elements are arranged at the end of an optical waveguide so as to receive radiation from different solid angle ranges. By corresponding evaluation of the signals supplied by the sensor elements, a temperature reading is obtained which, while being relatively independent of the placement of the probe head in the ear, is likewise representative of an intermediate value which does not correspond to the true tympanic temperature.